Hinge differential for rotative wing aircraft



Jul 13, 1937. R. R. HAYS HINGE DIFFERENTIAL FOR ROTATIVE WING AIRCRAFT Filed June 22, 1936 '55 such as is embodied in this invention.

Patented July 13, 1937 r i UNITED STATES PATENT OFFICE HINGE DIFFERENTIAL FOR IROTATIIVE Y WING-AIR RAFT Russell R. Hays, Wellsville, Kans.

Application June 22, 1936, Serial No. 86,473

11 Claims- (Cl. 244-17).

This invention relates to aircraft having sus- I Figure 2 is a side elevational view of the same, taining rotors and more particularly to a hinge hinge mechanism. mounting for the individual blades of such rotors, Figure 3 is a diagrammatic view in plan form being a continuation in part of' my co-pending of a sustaining rotor showing the position of the application, Serial Number 84,923, filed June 12, blade tips in degrees of rotation relative to the 1936. direction of travel, and

An object of this invention is broadly the pro- Figure 4 is a somewhat diagrammatic sectional vision of a pitch differential mechanism, autoview taken along the line 4-4 of Fig. 1 showing matically operative-on a sustaining rotor in transthe relative degrees of articulation and the resultlO lation to produce a minimum pitch of the blades ant pitch variation occurring through rotary at forward moments of rotation, and a maximum swinging movement of the blade. pitch at moments when they are retreating rela- Referring to Figs. 1 and 2, a main shaft 8 contive to the direction of travel, these moments of taining the rotor axis AA, has a head member maximum and minimum pitch occurring within 2 solidly afiixed to it and carrying the aligned Substantially 90 degrees h other during robolts 3-3 in its ends which form a horizontal 15 tation of the blades about the rotor axis. axis BB for the hangers 44 of the hinge mem- Another object is the provision of a mechanism her 5, the outer side of which carries the hangers in which the drag as transmitted by the blades 6 6 in which is solidly affixed the bolt 1 com- 'of a rotor having articulative blades, will tend prising an axis CC on which is journaled the to remain constant at all moments of rotation, horizontal projections 8-8 of the vertical hinge and in keeping with this objective the tip of-each member 99 in the ends of which are mounted blade will tend to describe a circlein a plane at aligned vertical bolts l0-'lll forming a vertical right angles to the mean radial position of the axis D'-D for the hinge hangers |il l of the blade during each revolution. hinge member l2, the outer end of which carries Yet another object is the provision of a hinge the hinge hangers l3-I3 in which is secured mounting for articulative blades in which'swingthe bolt I 4 forming an axis EE on which is ing movement within the plane of rotation of journaled the hanger l5 of the hinge section IS, the blade occurs about an axis lying in a vertical the outer end of this section being rigidly seplane containing the longitudinal axis of the cured to the butt of the blade I! in such a manblade, the blade axis making anacute angle with ner as to g ve a pitch Setting of the blade this hinge axis. keeping with accepted practice.

Still another object is the provision of a hinge The longitudinal axis F--F of the blade ll mounting having dual articulation and appropriintersects the axes EE, DD, CC, BB, and ate stops for efiecting a wider range of pitch AA in its mean coning position and mean 5 variation as a result of swinging movement of radial position, at which time the face I 9 of the the blade within its planev of rotation, than can stop20 which is a part of the hinge member 5, be efiectedby a single hinge mounting, being an contacts the head member 2 thereby limiting adaptation to a vertical plane of the horizontal the upward pivoting of the hinge member 5 about hinge mounting described in my co-pending apthe axis BB at this point, and in a similar 40 plication Serial Number 84,923. manner the face 2| of the stop 22 at the outer 40 Another object is the provision of a hinge and under side of the hinge member 5 contacts mounting for such a blade providing dual articuthe hinge. member 9-9 to stop downward pivotlation as a result of swinging of the blade bothing of the hinge member 9-9 about the axis transversely and within its plane of rotation, such CC at this point. The face 23 of the stop 26 articulation occurring simultaneously about two on the hinge member l2--contacts ,the projection 45 different axes during every 90 degrees of rota- 8 of the hinge member 9-9 stopping forward tion of the blade about the main rotor axis. pivoting of the hinge member l2 about the axis All of which is with the object of increasing the DD at this point, and the face 25 of stop 26 efliciency and smoothness of operation of the roat the outer and rearward side of the hinge memtor, as will become more apparent in reading the her I2 contacts the hinge member l5 at the same following description in conjunction with the time stopping rearward pivoting of the hinge accompanying drawing in which: member l6 about the axis EE.

Figure 1 is a view in plan form oi one such In operation, the advantages of this method blade mountingproviding apitch differentiation of articulatively mounting the blades become more apparent from consideration of the pitch requirements resultant to translation with a sus taining rotor. The dissymmetry of airflow occurring at cross-wind moments of rotation is generally recognized. However, the fact that the forwardly working blades deflect the airflow to an a smaller or negative tip setting is desired on the I forwardly working blade than on the advancing blade, no mechanism has hitherto been available which would provide such a pitch setting without imposing either an excessive pitch setting at rearwardly working moments of rotation, or else too small a pitch setting on the retreating blade when the proper pitch setting was given to the advancing blade.

This defect has its source in the fact that the feathering mechanisms now in use vary their pitch at opposite moments of rotation by the same degree. In other words, an increase in pitch of the blade at one side by a given amount results in an equal decrease in pitch of the same blade 180 degrees of rotation about the rotor axis later. Whereas, what is desired is a minimum pitch at forward working moments of the 'blade and a maximum pitch 90 degrees of rotation later at retreating moments of rotation.

Withthis objective in mind, certain mechanical movements are utilized in achieving such pitch variation that are more significant than a brief examination of the structure shown would presuppose. The first of these is that in a universally mounted articulative blade system, and more particularly in conjunction with feathering, dissymmetry of airflow with a resultant dissymmetry in the lift and drag on the individualblades, sets up a harmonic oscillation of the blade, not merely transversely but also within the plane of rotation, the result being that the tip'of the blade describes one clockwise circle, Fig. 4, or near circle to every complete rotation of the blade about the main rotor axis in the direction shown in Fig. 3.

Thus the fundamentals of the pitch differential disclosed compn'se from a mechanical standpoint, a. rotating member, movement of which at any moment of rotation during translation, produces movement of or about at least two axes, one of which is .relatively fixed in its position to the main rotor axis A-A. This basic principle, of a rotating member acting in conjunction with another member or members mounted upon a plurality 'of pivotal axes, one of .which is relatively fixed, to produce the desired feathering action in a rotor of this type, is the essence of this disclosure; and the fact, that in thisinstance a simplified combination of hinge members and stops acting inv conjunction with a universally articulated blade achieves this result with a high degree of simplicity, does not preclude the application of the same basic idea to rotors of' of rotation, and finally of the two in combination with rotation of the blade tip. In the first instance, the change of pitch resultant totransverse swinging is discussed at length in my copending application Serial Number 84,923.

Referring to Fig. 4, the blade section S, in moving about the circular path V, is seen to move transversely a distance 0 above the plane of rotation PP at which time, due to the stop 20, Figs. 1 and 2, preventing upward pivoting of the hinge member 5, the blade pivots about the axis CC with a decrease in pitch proportional to the angle Y, whereas with downward movement through thedistance 0 below the plane.

PP, the pivoting is about the axis BB, and since the angle 1; made by the axis BB with the blade axis F-.-F is greater than the angle Y, a smaller decrease in pitch occurs during downward swinging movement of the blade than during upward swinging movement.

In an analogous manner swinging of the blade .within its plane of rotation takes place about The degree of swinging within the plane PP being determined by the distance of the axes D-D and EE from the rotor axis A-A, it follows that -for any specific blade such valuesof the angles X, Y, Z, and W can be used, as in this instance; where the vertical angle W is smaller than the larger horizontal angle X, and

the larger vertical hinge angle Z is greater than the smaller horizontal hinge angle Y, so that with approximately equal values of the distances N and 0, it is readily apparent that the minimum pitch of the blade occurs at S1, Fig. 4, or at such moments as the blade is forwardly rotating at'the point 0 degrees of Fig. 3, whereas the maximum pitch occurs at S2 or at retreating moments of rotation at the point 90 degrees of Fig. 3.

The fact that increasing oscillation of the blade tip with a consequent increase in the radius of the circular path V, is accompanied by an equal degree of'pitch variation is apparent from the fact that all pitch variation starts the common point at S in the center of the circle V.

What is not so apparent is that the drag of the blades as transmitted to the rotor center should remain constant at all phases of the blade's rotation about the circular path V. This condition resides in the interaction between the circular paths V and Q. Thus since the highest and lowest travel of the blade to the mean'plane of rotation P--P occurs at S1 and S3 at which moments of rotation the blades are aligned with the direction of travel T, the oscillation takes the form of a rearward pitching moment at this phase of rotation, the drag at the rotor center being equal to the sine of the angle made by the blade with the plane PP times the lift.

And in a similar manner, the extremes of swinging movement S2 and S4 within the plane of rotation PP, occur at cross-wind moments of rotation of the rotor. Thus, since the lift and drag are transmitted to the rotor center through the medium of centrifugal forces resultant to disalignment of articulative blades, it follows that the drag transmitted to the rotor center at these moments is equal to'the sine of the angle made by the blade with its mean radial position times the centrifugal forces working on the blade, and

thus since the angles of disalignment in both 7 smoothness of operation through such a constant drag and by reason of such pitch variation, being self evident, what I claim is: v

1. In an aircraft having a rotative hub and sustaining blades mounted thereon, a hinge mounting for the individual. blades on said hub comprising a plurality of pivotal axes offset relative to the system's center and angularly dis-' posed .relative to the system's plane of rotation and to each other, one of said axes being more oifset than the other, and stops limiting the pivotal movement of the outer of these axes about the inner axis.

- 2. In an aircraft having a bladed sustaining rotor, a hub, a hinge mounting for the individual blades on said hub comprising a plurality of pivotal axes lying within a substantially vertical plane and making an acute angle with each other, and a plurality of pivotal axes lying substantially within a horizontal plane and making an acute angle with each other.

3. In an aircraft having a bladed sustaining rotor, a hub, a hinge mounting on said hub for the individual blades comprising a plurality of pivotal axes lying within a substantially vertical plane and making an acute angle with each other, and at least onev of said axes making an acute angle with the longitudinal axis of the blade;

and a plurality of pivotal axes lying substantially within a horizontal plane and making an acute angle with each other and with the longitudinal axis of the blade forwardly to the direction of the blades rotation about the rotor 4; In an aircraft having a'bladed sustaining rotor, a hub, a hinge mounting on said hub for,

the individual blades comprising aseries of hinge members connected by pivotal axes to form a rotary movement by such a degree as to provide a maximum and minimum pitch setting during substantially 90 degrees of rotation-of the blade about the rotor axis.

-5.. In an aircraft having a bladed sustaining rotor, a hub, a hinge mounting on said hub for the individual blades comprising a series of hinge members connected by pivotal axes to form a plurality of hinges operative about their respective axes in response to rotary. articulative movement of the blade, said pivotal axes substantially intersecting the longitudinal axis of the blade with one of said axes in a vertical-planemaking a smaller angle with the blade axis than that made by any of the other axes, and another axis in the vertical plane making a greater angle with said blade axis then the: smaller of the angles made by said pivotal axes lying in a horizontal plane with saidblade axis, and stops actively associated with the hinge member alternately limiting pivotal movement of said hinge members by such a degree as to provide a minimum 5 pitch setting of the blade during such phases as it is rotating forwardly to the rotors direction of travel, and a maximum pitch settingat such phases as it is retreating relative to the rotor's direction of travel.

6. In an aircraft having a bladed sustaining rotor, a hub, a universal mounting on said hub for the individual blades comprising a series of hinge members having a plurality of pivotal axes lying in at least two planes, stops alternating 15 pivotal movement of the members of said universal mounting about their respective pivotal axes in response to radial rotation of the blade about its mean radial position whereby each pivotal axis co-acts with each pivotal axis in the 0 other plane to vary the pitch of the blade during some phase of each complete revolution of the blade about the main rotor axis. I

7. In an aircraft having a bladed sustaining rotor, a hub, a universal mounting on said hub 2 for the individual blades comprising a series of hinge members the pivotal axes of which make acute angles with each other in at least two planes, means alternating movement of said hinge members about said pivotal axes, and said piv- Q- .of said hinge members about said pivotal axes of rotation.

in response to movement of the blade from its mean radial position whereby the pitch of each blade is varied asymmetrically at opposed phases of rotation. 9. In a rotor, a hub, blades, means for securing said blades to said hub so that their pitch may be varied, means for predetermining the mean pitch variation of the blades of the rotor at different phases of rotation by asymmetrically varying the pitch of the blades at different phases of each rotation-of the rotor.

10. In a bladed rotor subject to a flow of fluid therethrough and non-parallel to the axis of rotation of the rotor, means for varying the pitch of the blades of said rotor, means for equalizing the drag of the blades. of said rotor including means for positively varying the mean pitch angle of the rotor at different phases of each rotation.

11. In a bladedrotor having at least one pair of oppositely extending substantially radial blades, said rotor being subject to a flow of fluid therethrough and non-parallel to the axis ofrotation'of the rotor, means for equalizing the lift on said oppositely extending blades by asymmetrically varying their pitch at varying phases of rotation, thereby positively varying the mean pitch of the rotor blades at corresponding phases RUSSELL a. HAYS.

DISCLAIMER 2.086,802.-Russell R. Hays, Wellsville, Kans. HINGE DIFFERENTIAL FOR Ro'm fivn H WING AIRCRAFT. Patent dated July 13, 1937. Disclaimer 'filed Decem- Ber 18, 1944,'by the patentee. 4 Hereby enters this disclaimer to claim 1'in said specification.

' [Ofiicial Gazette January 30, 1945.] 

